in src/jsii/jsii-utils.ts [259:273]
function isDeclaration(x: ts.Node): x is ts.Declaration {
return (
ts.isClassDeclaration(x) ||
ts.isNamespaceExportDeclaration(x) ||
ts.isNamespaceExport(x) ||
ts.isModuleDeclaration(x) ||
ts.isEnumDeclaration(x) ||
ts.isEnumMember(x) ||
ts.isInterfaceDeclaration(x) ||
ts.isMethodDeclaration(x) ||
ts.isMethodSignature(x) ||
ts.isPropertyDeclaration(x) ||
ts.isPropertySignature(x)
);
}